A narrow tube is placed vertically in a pan of water, and the water rises in the tube to 4.0 cm above the level of the pan. The surface tension in the liquid is lowered to one-half its original value by the addition of some soap. What happens to the height of the liquid column in the tube?

Pascal's principle: If an external pressure is applied to a confined fluid, the pressure at every point within the fluid increases by that amount.
Archimedes' principle: The buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by that object.

Bernoulli's principle: Where the velocity of fluid is high, the pressure is low; and where the velocity is low, the pressure is high.